Cypress CY7B991 User Manual

Document Number: 38-07138  Rev. *B

Page 2 of 19

REF

I

Reference frequency input. This input supplies the frequency and timing against which all functional 
variations are measured.

FB

I

PLL feedback input (typically connected to one of the eight outputs).

FS

I

Three level frequency range select. See 

.   

1F0, 1F1

I

Three level function select inputs for output pair 1 (1Q0, 1Q1). See 

2F0, 2F1

I

Three level function select inputs for output pair 2 (2Q0, 2Q1). See 

3F0, 3F1

I 

Three level function select inputs for output pair 3 (3Q0, 3Q1). See 

4F0, 4F1

I

Three level function select inputs for output pair 4 (4Q0, 4Q1). See 

TEST

I

Three level select. See 

on page 4 under the 

1Q0, 1Q1

O

Output pair 1. See 

.

2Q0, 2Q1

O

Output pair 2. See 

.

3Q0, 3Q1

O

Output pair 3. See 

.

4Q0, 4Q1

O

Output pair 4. See 

.

V

CCN

PWR

Power supply for output drivers.

V

CCQ

PWR

Power supply for internal circuitry.

GND

PWR

Ground.

1

2

3

4

32 31 30

17

16

15

14

18 19 20

5

6

7

8

9

10

11

12

13

29

28

27

26

25

24

23

22

21

3F

0

FS

V

REF

GND

TEST

2F

1

FB

2Q1

2Q0

CCQ

2F0

GND

1F1

1F0

V

CCN

1Q0

1Q1

GND

GND

3Q1

3Q0

CC

N

V

CC

N

V

3F1

4F0

4F1

V

CCQ

V

CCN

4Q1

4Q0

GND

GND

CY7B991

CY7B992